Speech Enhancement Using Small Microphone Arrays with Optimized Directivity

Authors:

Dörbecker, M.

Book Title:

Proceedings of International Workshop on Acoustic Echo and Noise Control (IWAENC)

Organization:

n.n.

Series:

5

Pages:

p.p. 100-103

Address:

London, Great Britain

Date:

Sep. 1997

Language:

English

Abstract

A common approach to enhance the quality of speech signals disturbed by acoustic background noise is the application of adaptive filtering techniques aiming at the reduction of the noise. However, in case of low SNR most of the currently known adaptive techniques result in a poor quality of the processed signal, which is caused by time-variant distortions of the speech signal and by the unnatural character of the remaining noise (e.g. in form of "musical tones"). An alternative approach, which does not affect the speech signal by time-variant distortions, is the application of a microphone array with a fixed directivity pattern aligned to the speaker's position, resulting in a suppression of spatial distributed noise sources. Within the scope of this paper it will be shown that - owing to the proposed optimization of the directivity pattern - even an array consisting of only two microphones may offer a performance comparable to state-of-the-art adaptive filtering techniques. Acoustic measurements related to electronic hearing aids confirm that the improvement of the SNR predicted by theory also holds for signals recorded in a real acoustic environment.

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